Collaborative Research: Novel Plasma Physics of Trapped Antimatter

这一奖项使人们能够探索未来研究物质和反物质之间不对称性的实验。物质在反物质上的普遍存在是物理学中最重要的无法解释的观测之一。正如目前所理解的，物理定律遵循对称性质，即预言两种形式的物质相等--这与我们的日常经验以及详细的天文观测结果不符。这种不一致表明，我们目前对物理定律的理解可能是不完整的。阿尔法是欧洲核子研究中心的一项跨学科反物质实验，它通过产生反氢并灵敏地测量其与氢原子的比较来测试这一概念。捕获反物质以产生反氢是一个等离子体物理问题，包括使用电场和磁场收集和操作大量带电粒子。这项由密歇根大学安娜堡分校和马奎特大学合作进行的项目将促进对这些实验中发生的新的等离子体物理过程的理解，并为未来可能的实验制定方案。该项目还支持开发互动科学展品，用于在威斯康星州密尔沃基的发现世界科学和技术中心以及美国物理学会等离子体物理分会年度会议期间的等离子体博览会上展示。从等离子体物理角度和粒子物理角度来看，囚禁反物质是新的。这些等离子体是如此之冷，陷阱中的磁场如此之强，以至于它们以一种通常的等离子体物理模型无法很好地描述的状态存在。具体地说，低温导致等离子体强烈耦合，这意味着它的行为更像是超临界流体或液体，而不是更常见的类似稀薄气体的行为。较强的外加磁场，加上较低的密度，也会导致等离子体被强烈磁化。目前理解的等离子体理论方法在这两种情况下都不适用。即将进行的研究将进一步发展最近的理论方法，将等离子体理论扩展到这些领域。这项工作将应用新开发的动力学理论和分子动力学模拟来促进对与等离子体相关的三个关键过程的理解：电子和正电子压缩、反质子冷却以及反质子和正电子的混合和复合。分子动力学模拟将被用来测试模型的开发。这些先进的模型将被应用于探索将正电子和反质子集合转化为反氢原子的更有效的方法。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This award enables an exploration of future experiments for studying asymmetry between matter and antimatter. The prevalence of matter over antimatter is one of the most important unexplained observations in physics. As currently understood, the laws of physics obey symmetry properties that predict equality between the two forms of matter – at odds with our everyday experience as well as detailed astronomical observations. Such an inconsistency suggests that our current understanding of the laws of physics may be incomplete. ALPHA is an interdisciplinary antimatter experiment at CERN that tests this notion by producing antihydrogen and sensitively measuring its properties in comparison with the hydrogen atom. Trapping antimatter to produce antihydrogen is a plasma physics problem, consisting of collecting and manipulating large collections of charged particles using electric and magnetic fields. This project conducted in collaboration between the University of Michigan - Ann Arbor and Marquette University will advance understanding of novel plasma physics processes that occur in these experiments and develop protocols for possible future experiments. The project also supports development of interactive science exhibits for display at the Discovery World Science and Technology Center in Milwaukee, WI and at the Plasma Expo during the American Physical Society Division of Plasma Physics annual meetings.Trapped antimatter is novel from a plasma physics perspective, as well as a particle physics perspective. These plasmas are so cold, and the magnetic fields of the trap are so strong, that they exist in a state that is not well described by the usual models of plasma physics. Specifically, the low temperature causes the plasma to be strongly coupled, which means that it behaves more like a supercritical fluid or a liquid, than the more common dilute-gas-like behavior. The strong applied magnetic field, in combination with the low density, also causes the plasma to be strongly magnetized. Currently understood methods of plasma theory do not apply in either of these circumstances. The research to be conducted will further develop recent theoretical approaches that extend plasma theory into these domains. The work will apply a newly developed kinetic theory and molecular dynamics simulations to advance understanding of three critical plasma-related processes: electron and positron compression, antiproton cooling, and mixing and recombination of antiprotons and positrons. Molecular dynamics simulations will be used to test the model development. The advanced models will be applied to explore more efficient ways to convert collections of positrons and antiprotons into antihydrogen atoms.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.